This invention relates generally to the field of computer operated robot arms and more particularly to method and apparatus for programming a cycle of operation. The invention has particular utility in connection with programmable robot arms of the type disclosed in Corwin et al. U.S. Pat. No. 3,920,972.
In systems of the type disclosed in Corwin et al. a hand held pendant is used to cause movement of a robot arm to a series of positions within either a Cartesian or a cylindrical coordinate system. At each such position the pendant may be further used to command the end of the robot arm to assume any desired orientation. Depending upon the sophistication of the robot, as many as three positional control buttons and three orientation control buttons may be provided on the pendant. Commands from the pendant are fed into a computer to command movement of the arm by coordinate extrapolation and transformation. Such coordinate transformation is required, because the robot arm is articulated and must accomplish translational movement of the end of the robot arm by combined rotational movements of different elements of the arm.
As each new position is reached and the appropriate orientation is achieved, the pendant is operated to cause programming or teaching of a location and velocity instruction which when executed in the automatic mode of operation directs the robot arm to achieve the designated position and orientation. These instructions then become part of a cycle of operation program which controls the operation of the robot arm in the automatic mode. In general the instructions so created and stored specify the position and orientation of the end of the robot arm in the world coordinate system, that is, the combination of coordinates defining position (X, Y, Z) and orientation (D, E, R). This enables the computer to calculate a straight line path between program points.
Each time a movement instruction is created for the operating control program, the operator is given the opportunity to create programming instructions defining an operation to be performed by the robot arm. These instructions may control the arm acceleration or velocity at the designated point or may adjust a process variable, such as the voltage for a welding electrode being carried by the arm. These instructions are created by operating a keyboard incorporated within a portable teaching station which is generally a separate unit from the pendant.
The robot system as described in Corwin et al. is extremely versatile and provides the operator with a broad range of options in defining operations to be performed by the arm. However, a price is paid for this versatility in that the operator is required to enter a substantial number of keystroke instructions into the computer each time an operation is defined or modified.
It is therefore seen that there is a need to provide apparatus and method which simplifies the programming of a computer operated robot arm without compromising the versatility afforded by keystroke programming.